In the most recent MSDN flash are the following updates to take note of – some new SharePoint SDK releases:
The August 2008 update of the SharePoint Server 2007 SDK contains documentation for new and improved features in the Infrastructure Update for Microsoft Office Servers and new conceptual, procedural, and reference information. You can also view the August update online.
See the latest additions to the Windows SharePoint Services SDK. Find conceptual overviews, programming tasks, and references for Windows SharePoint Services. View the Windows SharePoint Services 3.0 SDK online.